LOS ANGELES (CBSLA.com) — New details are emerging in the investigation of how the LAX shooting suspect arrived at the airport and what those who lived closest to him may have known.

Paul Ciancia, reportedly an unemployed motorcycle mechanic raised in Pennsylvania, is accused of opening fire in Terminal 3 at LAX on Friday morning, specifically targeting TSA agents.

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Agent Gerardo I. Hernandez, 39, was fatally shot in the incident. Two other TSA agents, Tony Grigsby, 36 and 54-year-old James Speer, were also wounded.

Six people were hurt, including Calabasas High School teacher Brian Ludmer, who was shot in the leg, before Ciancia was taken down by authorities.

PHOTOS: Shooting At LAX

Officials are remaining tight-lipped about the details of the investigation, though various FBI sources have said agents know how the 23-year-old Ciancia was transported to the airport.

Investigators said surveillance footage shows Ciancia being dropped off at the airport by a friend driving a black Hyundai. The driver of the car reportedly had no idea Ciancia was armed and is not believed to have been involved in the rampage.

FBI agents on Monday returned for a second time to the apartment where Ciancia was said to have lived and escorted a man identified as his roommate from the unit to his vehicle. The roommate was seen getting into a black Hyundai before driving off, though it was unclear if that car was used to drive Ciancia to the airport Friday. He refused to speak to reporters.

A Suzuki motorcycle parked outside of the Sun Valley apartment complex was found to be registered to Ciancia.

A second man was also seen being escorted from the Sun Valley property. It was unclear what his connection might be to the investigation.

A woman who said she knows Ciancia and his three roommates told CNN he plotted the attack days in advance, and asked a roommate to drive him to the airport. According to the unidentified woman, Ciancia told roommates his father was sick and he had to return home to deal with family issues.

The friend also told CNN that Ciancia had been upset by the revelations of NSA spying and also believed TSA abused their power.

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CBS News Senior Correspondent John Miller, a former LAPD and FBI official, reports Ciancia concealed the weapon in a rolling suitcase with a backpack on top by cutting a hole in the bottom of the backpack and the top of the suitcase. The rifle was reportedly standing up inside the two bags, according to Miller.

According to Miller’s sources, Ciancia entered through the exit lane that passengers use when deplaning and headed down the concourse. At that point, investigators said, Ciancia was hunting for TSA officials.

The FBI said Ciancia left behind a signed handwritten note stating that he had “made the conscious decision to try to kill” multiple TSA employees.

Roughly a minute after shots were fired, officers responded to radio calls and engaged the suspect in gunfire. Ciancia was reportedly shot four times, including once in the head.

He remains hospitalized at UCLA Medical Center.

“This is our worst nightmare,” said Los Angeles Airport Police Chief Patrick Gannon. “People used to ask me what do you worry about as being the airport police chief; this scenario is the one that would keep me up at night.”

Aaron Basco, Ciancia’s next door neighbor, said he returned home to a heavy police presence Friday before seeing a picture of his neighbor on television.

“Every time I passed him, not much eye contact,” Basco said. “Didn’t really say much, so was a really quiet guy.”

A sealed warrant was served to the property Friday. Neighbors told KCAL9’s Suraya Fadel they saw several boxes, papers and a laptop confiscated from the unit.

Earlier in the day, Ciancia’s family issued a statement read by an attorney. It said, in part:

“Paul is our son and brother. We will continue to love him and care for him. We will support him during the difficult times ahead. While we do not mean to minimize the grief and stress experienced by many other families, we hope that the public will understand that this is a very difficult time for our family too.”

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